How it works?
These mirrors have a reflective coating applied in a thin sparse layer due to which it is called as half-silvered surface. The name, half-silvered is due to its reflective molecules coat on the glass that is done so sparsely that only about half the molecules needed to make the glass an opaque mirror are applied. The half-silvered surface will reflect about half the light that strikes its surface, while letting the other half go straight through.
The effect happens primarily due to the lighting of the two rooms. The room in which the glass looks like a mirror has a bright light, so that there is plenty of light to reflect back from the mirror’s surface. The other room, in which the glass looks like a window, is kept dark, so there is very little light to transmit through the glass.
The Problem: 2 way mirrors are great but it could cause serious concerns especially on privacy if installed in hotels or other public places. How to determine if a mirror is 2 way and avoid problems (may be). This is not to scare you, but to make sure that you are aware.
Many of the hotels and textile showrooms in the present times cheat the customers this way & watch privately. It could be just to know more about their products (who knows).
When we visit toilets, bathrooms, hotel rooms, changing rooms, etc., how many of you know for sure that the seemingly ordinary mirror hanging on the wall is a real mirror, r actually a 2-way mirror i.e., they can see you, but you can’t see them). There have been many cases of people installing 2-way mirrors in female changing rooms or bathroom or bedrooms. It is very difficult to positively identify the surface by just looking at it. So, how do we determine with any amount of certainty what type of mirror we are looking at?
This simple test will help:
Position the tip of your fingernail touching the reflective plane and if there is a GAP between your fingernail and the image of the nail, then it is a GENUINE mirror. However, if your fingernail DIRECTLY TOUCHES the image of your nail, then BEWARE, It is a 2-way mirror! (There is someone seeing you from the other side). So remember, every time you see a mirror, do the “fingernail test.” It doesn’t cost you anything. It is simple to do. This is a really good thing to do.
The reason there is a gap on a real mirror, is because the silver is on the back of the mirror UNDER the glass, whereas with a two-way mirror, the silver is on the Surface. Keep it in mind! Make sure and check every time you enter in hotel rooms. May be someone is making a film on you.
Other way to verify the presence of transparent mirror is by rapping at it lightly. A mirror generally has a back support and thus will produce a dull thud sound. If the mirror is 2 – way i.e. transparent, it will create a hollow sound.